Sturm Ruger and American Outdoor Brands reversed their gains within an hour of the market open. ShotSpotter, a maker of gunshot detection software, went public on June 8 and reached an all-time high during the rally.

Gun stocks tend to rally after mass-shooting incidents. During the Obama administration, heightened conversation about gun control raised speculation that people would want to buy firearms sooner rather than later before any regulations were tightened.

In its first-quarter earnings released last month, Sturm Ruger indicated that demand from gun retailers fell after a period of stronger-than-normal demand that was likely caused by political campaigning for the November elections.

The broader market was little changed on ahead of the Federal Reserve's expected interest-rate increase later on Wednesday.

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Shooting at congressional baseball practice

A police officer mans a shooting scene after a gunman opened fire on Republican members of Congress during a baseball practice near Washington in Alexandria, Virginia, June 14, 2017. REUTERS/Joshua Roberts

Police survey a shooting scene after a gunman opened fire on Republican members of Congress during a baseball practice near Washington in Alexandria, Virginia, June 14, 2017. REUTERS/Joshua Roberts

Police investigate a shooting scene after a gunman opened fire on Republican members of Congress during a baseball practice near Washington in Alexandria, Virginia, June 14, 2017. REUTERS/Joshua Roberts

U.S. Rep. Mo Brooks (R-AL) talks to reporters after a gunman opened fire on Republican members of Congress during a baseball practice near Washington in Alexandria, Virginia, U.S., June 14, 2017. REUTERS/Joshua Roberts

People walk away from the Eugene Simpson Stadium Park in Alexandria, Virginia, U.S., on Wednesday, June 14, 2017. The third highest ranked U.S. House Republican and at least four others were injured Wednesday morning in a shooting at a congressional baseball practice field the Alexandria neighborhood witnesses said. Photographer: Andrew Harrer/Bloomberg via Getty Images

A police officer stands next to a vehicle with a damaged window near the Eugene Simpson Stadium Park in Alexandria, Virginia, U.S., on Wednesday, June 14, 2017. The third highest ranked U.S. House Republican and at least four others were injured Wednesday morning in a shooting at a congressional baseball practice field the Alexandria neighborhood witnesses said. Photographer: Andrew Harrer/Bloomberg via Getty Images

A police officer stands guard near the Eugene Simpson Stadium Park in Alexandria, Virginia, U.S., on Wednesday, June 14, 2017. The third highest ranked U.S. House Republican and at least four others were injured Wednesday morning in a shooting at a congressional baseball practice field the Alexandria neighborhood witnesses said. Photographer: Andrew Harrer/Bloomberg via Getty Images

People stand past crime scene tape near the Eugene Simpson Stadium Park in Alexandria, Virginia, U.S., on Wednesday, June 14, 2017. The third highest ranked U.S. House Republican and at least four others were injured Wednesday morning in a shooting at a congressional baseball practice field the Alexandria neighborhood witnesses said. Photographer: Andrew Harrer/Bloomberg via Getty Images

Police tape is viewed near the crime scene of an early morning shooting in Alexandria, Virginia, June 14, 2017.
At least five people people including a top Republican congressman were wounded in a Washington suburb early Wednesday morning when a shooting erupted as they practiced for an annual baseball game between lawmakers. Senior congressman Steve Scalise was shot in the hip, according to fellow Republican lawmaker Mo Brooks who told CNN at least two law enforcement officers and one congressional staffer were also shot in the incident in Alexandria, Virginia.
/ AFP PHOTO / Brendan Smialowski (Photo credit should read BRENDAN SMIALOWSKI/AFP/Getty Images)

ALEXANDRIA, VA - JUNE 14: Investigators gather at Eugene Simpson Field, the site where a gunman opened fire June 14, 2017 in Alexandria, Virginia. Multiple injuries were reported from the instance, the site where a congressional baseball team was holding an early morning practice, including House Republican Whip Steve Scalise (R-LA) who was reportedly shot in the hip. (Photo by Win McNamee/Getty Images)

ALEXANDRIA, VA - JUNE 14: Members the FBI survey the damages possibly caused by gun shots on a wall at the site of this morning's shooting at Eugene Simpson Stadium Park June 14, 2017 in Alexandria, Virginia. U.S. House Majority Whip Steve Scalise (R-LA) was among five wounded in the attack, including the suspected gunman, as Republican congressional members practiced for a charity baseball game. (Photo by Alex Wong/Getty Images)

ALEXANDRIA, VA - JUNE 14: A member of the FBI Evidence Response Team collects evidence at a vehicle whose window is broken at the site of this morning's shooting at Eugene Simpson Stadium Park June 14, 2017 in Alexandria, Virginia. U.S. House Majority Whip Steve Scalise (R-LA) was among five wounded in the attack, including the suspected gunman, as Republican congressional members practiced for a charity baseball game. (Photo by Alex Wong/Getty Images)

ALEXANDRIA, VA - JUNE 14: Members of the FBI Evidence Response Team collect evidence at the site of this morning's shooting at Eugene Simpson Stadium Park June 14, 2017 in Alexandria, Virginia. U.S. House Majority Whip Steve Scalise (R-LA) was among five wounded in the attack, including the suspected gunman, as Republican congressional members practiced for a charity baseball game. (Photo by Alex Wong/Getty Images)

US Representative Chuck Fleischmann, Republican of Tennessee, speaks to the media about a shooting incident during a Congressional baseball practice in Virginia after returning to the US Capitol in Washington, DC, June 14, 2017.
Several people including a top Republican congressman were wounded in a Washington suburb early Wednesday morning when a gunman opened fire as they practiced for an annual baseball game between lawmakers. / AFP PHOTO / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

US Senator Bernie Sanders, Independent of Vermont, gets on an elevator as he heads to a vote at the US Capitol in Washington, DC, June 14, 2017, following a report that the shooter in the attack targeting Congressmen in nearby Virginia was a Sanders supporter.
Several people including a top Republican congressman were wounded in a Washington suburb early Wednesday morning when a gunman opened fire as they practiced for an annual baseball game between lawmakers. / AFP PHOTO / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

US Speaker of the House Paul Ryan walks to his office after making a statement on the House floor at the US Capitol in Washington, DC, June 14, 2017, following a shooting incident targeting Congressmen in nearby Virginia.
Several people including a top Republican congressman were wounded in a Washington suburb early Wednesday morning when a gunman opened fire as they practiced for an annual baseball game between lawmakers. / AFP PHOTO / SAUL LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

ALEXANDRIA, VA - JUNE 14: A marker is placed next to a piece of evidence at the scene of this morning's shooting at Eugene Simpson Stadium Park June 14, 2017 in Alexandria, Virginia. U.S. House Majority Whip Steve Scalise (R-LA) was among five wounded in the attack, including the suspected gunman, as Republican congressional members practiced for a charity baseball game. (Photo by Alex Wong/Getty Images)

ALEXANDRIA, VA - JUNE 14: Investigators search for evidence at the scene of this morning's shooting at Eugene Simpson Stadium Park June 14, 2017 in Alexandria, Virginia. U.S. House Majority Whip Steve Scalise (R-LA) was among five wounded in the attack, including the suspected gunman, as Republican congressional members practiced for a charity baseball game. (Photo by Alex Wong/Getty Images)

WASHINGTON, DC - JUNE 14: The Peace Monument at the U.S. Capitol is shown, on June 14, 2017 in Washington, DC. This morning House Majority Whip Steve Scalise (R-LA) three others were shot by a gunman during Congressional baseball practice in Alexandria, Virginia. (Photo by Mark Wilson/Getty Images)